feat: Add command which moves to EOD

cmd/stfs-eod/main.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"flag"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+// See https://github.com/benmcclelland/mtio
+const (
+	MTIOCTOP = 0x40086d01 // Do magnetic tape operation
+	MTEOM    = 12         // Goto end of recorded media (for appending files)
+)
+
+// Operation is struct for MTIOCTOP
+type Operation struct {
+	Op    int16 // Operation ID
+	Pad   int16 // Padding to match C structures
+	Count int32 // Operation count
+}
+
+func main() {
+	file := flag.String("file", "/dev/nst0", "File of tape drive to open")
+	record := flag.Int("record", 0, "Record to seek too")
+
+	flag.Parse()
+
+	f, err := os.OpenFile(*file, os.O_RDONLY, os.ModeCharDevice)
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+
+	syscall.Syscall(
+		syscall.SYS_IOCTL,
+		f.Fd(),
+		MTIOCTOP,
+		uintptr(unsafe.Pointer(
+			&Operation{
+				Op:    MTEOM,
+				Count: int32(*record),
+			},
+		)),
+	)
+}